MIFEPRISTONE PREVENTS THE EXPRESSION OF LONG-TERM BEHAVIORAL SENSITIZATION TO AMPHETAMINE

Three weeks following intermittent amphetamine exposure (2.5 mg/kg/day for 5 days), rats showed an enhanced locomotor response to an ampheta mine challenge. Mifepristone (20 mg/kg) given 45 min prior to the chal lenge completely prevented the expression of amphetamine hyperresponsi veness. The glucocorticoid antagonist did not affect the locomotor res ponse to amphetamine in drug-naive rats. These data demonstrate for th e first time that glucocorticoid receptor antagonist treatment may pre vent long-term hyperreactivity to drugs of abuse in individuals with a drug history.